Method of manufacturing polycrystalline silicon layer, and method of manufacturing transistor having the polycrystalline silicon layer

ABSTRACT

An embodiment is directed to a method of manufacturing a polycrystalline silicon layer, the method including providing a crystallization substrate, the crystallization substrate having an amorphous silicon layer on a first substrate, providing a reflection substrate, the reflection substrate having a first region with a reflection panel therein and a second region without the reflection panel, disposing the crystallization substrate and the reflection substrate on one another, and selectively crystallizing the amorphous silicon layer by directing a laser beam onto the crystallization substrate and the reflection substrate, and reflecting the laser beam from the reflection panel.

BACKGROUND

1. Field

Embodiments relate to a method of manufacturing a polycrystallinesilicon layer, and a method of manufacturing a transistor having thepolycrystalline silicon layer.

2. Description of the Related Art

In general, a thin-film transistor having a polycrystalline siliconlayer may exhibit high electron mobility and may be suitable for acomplementary metal-oxide semiconductor (CMOS) circuit. A thin-filmtransistor having a polycrystalline silicon layer may be used for, e.g.,a switching device of a high-resolution display panel and a projectionpanel that requires a large amount of light.

A method of crystallizing amorphous silicon into polycrystalline siliconmay include a solid phase crystallization (SPC) operation, in which anamorphous silicon layer is annealed for several hours to tens of hoursat a temperature of about 700° C. or less. A method of crystallizingamorphous silicon into polycrystalline silicon may include an excimerlaser annealing (ELA) operation in which a part of an amorphous siliconlayer is heated to a high temperature for a very short time by scanningexcimer layer onto the amorphous silicon layer, thereby crystallizingthe amorphous silicon layer. A method of crystallizing amorphous siliconinto polycrystalline silicon may include a metal induced crystallization(MIC) operation that utilizes a phenomenon that a phase change from anamorphous silicon layer to a polycrystalline silicon layer is induced bymetal, such as nickel, palladium, gold, or aluminum, by allowing themetal to contact the amorphous silicon layer or injecting the metal intothe amorphous silicon layer. A method of crystallizing amorphous siliconinto polycrystalline silicon may include a metal induced lateralcrystallization (MILC) method, in which crystallization of amorphoussilicon sequentially occurs as silicide generated by a reaction betweenmetal and silicon continuously propagates to a side surface.

SUMMARY

An embodiment is directed to a method of manufacturing a polycrystallinesilicon layer, the method including providing a crystallizationsubstrate, the crystallization substrate having an amorphous siliconlayer on a first substrate, providing a reflection substrate, thereflection substrate having a first region with a reflection paneltherein and a second region without the reflection panel, disposing thecrystallization substrate and the reflection substrate on one another,and selectively crystallizing the amorphous silicon layer by directing alaser beam onto the crystallization substrate and the reflectionsubstrate, and reflecting the laser beam from the reflection panel.

The crystallization substrate may have a buffer layer between the firstsubstrate and the amorphous silicon layer.

The first substrate may include a transparent material, the laser beampassing through the first substrate.

The first substrate may be a glass substrate.

The reflection substrate may include a second substrate, the reflectionpanel being a pattern on the second substrate, and a protection filmarranged on the second substrate to cover the reflection panel.

The second substrate may include a transparent material, the laser beampassing through the transparent material.

The second substrate may be glass or quartz.

The reflection panel may include a metal that is capable of reflectingthe laser beam, the laser beam being reflected from the metal to thecrystallization substrate.

The metal may have a reflectance of 50% or higher with respect to thelaser beam.

The protection film may include an oxide, a nitride, or an organicmatter, the laser beam passing through the protection film.

The protection film may be a single layer formed of an oxide, a nitride,or an organic material, or the protection film may be a plurality oflayers, each layer being formed of an oxide, a nitride, or an organicmaterial.

In the disposing of the crystallization substrate and the reflectionsubstrate on one another, the crystallization substrate and thereflection substrate may be brought into contact with each other so thatthe amorphous silicon layer faces the reflection panel.

Selectively crystallizing the amorphous silicon layer may includedirecting the laser beam in a direction from the crystallizationsubstrate toward the reflection substrate, and forming a polycrystallinesilicon layer by crystallizing a first area of the amorphous siliconlayer corresponding to the first region of the reflection substrate asthe laser beam directed toward the reflection substrate is reflected bythe reflection panel.

The forming of the polycrystalline silicon layer may include allowingthe laser beam to pass through the first area of the amorphous siliconlayer, and crystallizing the first area of the amorphous silicon layerby using the reflection panel in the first region of the reflectionsubstrate to reflect the laser beam passing through the first area ofthe amorphous silicon layer onto the first area of the amorphous siliconlayer.

The method may further include allowing the laser beam to pass through asecond area of the crystallization substrate and the second region ofthe reflection substrate, wherein the second area of the amorphoussilicon layer is not crystallized and remains as the amorphous siliconlayer after the laser beam passes through the second area of theamorphous silicon layer corresponding to the second region of thereflection substrate.

The laser beam may be scanned in a direction perpendicular to thereflection panel.

The method may further include disassembling the crystallizationsubstrate and the reflection substrate, after selectively crystallizingthe amorphous silicon layer.

Another embodiment is directed to a method of manufacturing atransistor, the method including providing a crystallization substrate,the crystallization substrate having an amorphous silicon layer on afirst substrate, providing a reflection substrate, the reflectionsubstrate having a first region with a reflection panel therein and asecond region without the reflection panel, disposing thecrystallization substrate and the reflection substrate on one another,forming a polycrystalline silicon layer by selectively crystallizing theamorphous silicon layer by directing a laser beam onto thecrystallization substrate and the reflection substrate, and reflectingthe laser beam from the reflection panel, and forming a channel regionand source and drain regions in the polycrystalline silicon layer.

The method may further include disassembling the crystallizationsubstrate and the reflection substrate, after selectively crystallizingthe amorphous silicon layer.

The method may further include forming a gate insulation film on thecrystallization substrate to cover the polycrystalline silicon layer,forming a gate electrode on the gate insulation film, the gate electrodecorresponding to the channel region of the polycrystalline siliconlayer, forming an interlayer insulation film on the gate insulation filmto cover the gate electrode, and forming a source electrode and a drainelectrode which are disposed on the interlayer insulation film andelectrically connected to the source region and the drain region of thepolycrystalline silicon layer, respectively.

Forming the polycrystalline silicon layer may include directing thelaser beam in a direction from the crystallization substrate toward thereflection substrate, and crystallizing a first area of the amorphoussilicon layer corresponding to the first region of the reflectionsubstrate as the laser beam directed toward the reflection substrate isreflected by the reflection panel.

The method may further include allowing the laser beam to pass through asecond area of the crystallization substrate and the second region ofthe reflection substrate, wherein the second area of the amorphoussilicon layer is not crystallized and remains as the amorphous siliconlayer after the laser beam passes through the second area of theamorphous silicon layer corresponding to the second region of thereflection substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages will become more apparent tothose of skill in the art by describing in detail example embodimentswith reference to the attached drawings, in which:

FIGS. 1-3 illustrate cross-sectional views of aspects of a method ofmanufacturing a polycrystalline silicon layer according to a firstexample embodiment;

FIGS. 4 and 5 illustrate cross-sectional views of stages in a method ofmanufacturing a thin-film transistor, according to a second exampleembodiment; and

FIG. 6 illustrates a cross-sectional view of an organic light-emittingdisplay device including a thin-film transistor, according to a thirdexample embodiment.

DETAILED DESCRIPTION

Korean Patent Application No. 10-2010-0071598, filed on Jul. 23, 2010,in the Korean Intellectual Property Office, and entitled: “Method ofManufacturing Polycrystalline Silicon Layer, and Method of ManufacturingThin-Film Transistor Comprising the Polycrystalline Silicon Layer,” isincorporated by reference herein in its entirety.

Example embodiments will now be described more fully hereinafter withreference to the accompanying drawings; however, they may be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art.

In the drawing figures, the dimensions of layers and regions may beexaggerated for clarity of illustration. It will also be understood thatwhen a layer or element is referred to as being “on” another layer orsubstrate, it can be directly on the other layer or substrate, orintervening layers may also be present. Further, it will be understoodthat when a layer is referred to as being “under” another layer, it canbe directly under, and one or more intervening layers may also bepresent. In addition, it will also be understood that when a layer isreferred to as being “between” two layers, it can be the only layerbetween the two layers, or one or more intervening layers may also bepresent. Like reference numerals refer to like elements throughout.

FIGS. 1-3 illustrate cross-sectional views of aspects of a method ofmanufacturing a polycrystalline silicon layer according to a firstexample embodiment. FIG. 1 schematically illustrates a crystallizationsubstrate 110. Referring to FIG. 1, the crystallization substrate 110may include a first substrate 111, a buffer layer 112, and an amorphoussilicon layer 113. The buffer layer 112 may be formed on the firstsubstrate 111. The amorphous silicon layer 113 may be formed on thebuffer layer 112.

The first substrate 111 may be formed of, e.g., a glass material that istransparent and includes SiO₂ as a main component. In anotherimplementation, the first substrate 111 may be formed of a materialtransparent to a laser beam used for crystallization, as describedfurther below.

The buffer layer 112 may prevent intrusion of foreign materials into thefirst substrate 111 and planarize a surface of the first substrate 111.The buffer layer 112 may be formed of, e.g., silicon nitride, siliconoxynitride, etc.

The amorphous silicon layer 113 may be formed on the buffer layer 112using, e.g., a chemical vapor deposition (CVD) method. The amorphoussilicon layer 113 formed by the CVD method may include gas such ashydrogen. The gas may generate a problem such as decreasing electronmobility. Thus, a dehydrogenation process may be performed in order toremove hydrogen the amorphous silicon layer 113. The dehydrogenationprocess may be omitted, depending on the particular requirements.

FIG. 2 schematically illustrates a reflection substrate 120. Referringto FIG. 2, the reflection substrate 120 may include a second substrate121, a reflection panel 122, and a protection film 123.

The second substrate 121 may be formed of, e.g., a transparent materialsuch as glass or quartz. In another implementation, the second substrate121 may be formed of another material transparent to the laser beam.

The second substrate 121 may be sectioned into a first region 121 a anda second region 121 b, with the reflection panel 122 being arranged inthe first region 121 a, and not in the second region 121 b. When a laserbeam is scanned toward a surface of the second substrate 121 where thereflection panel 122 is arranged, the laser beam proceeding toward thefirst region 121 a is reflected by the reflection panel 122. The laserbeam proceeding toward the second region 121 b passes through the secondsubstrate 121, as described below.

The reflection panel 122 may be patterned on the second substrate 121.For example, the reflection panel 122 may be arranged in the firstregion 121 a of the second substrate 121, but not in the second region121 b of the second substrate 121. The reflection panel 122 may beformed of, e.g., metal, that may reflect the laser beam. For example,the reflection panel 122 may be formed of metal that may reflect a laserbeam by 50% or higher. The reflection panel 122 may be formed by, e.g.,forming a metal layer on the second substrate 121 and then patterningthe metal layer.

The protection film 123 may be formed on the second substrate 121 tocover the reflection panel 122. The protection film 123 may be formed tocover not only the reflection panel 122 but also the second region 121 bof the second substrate 121. The protection film 123 may be formed of,e.g., an oxide, a nitride, or an organic matter, transparent to thelaser beam.

The protection film 123 may be a single layer, e.g., formed of oneselected from the group of oxide, nitride, and an organic compound. Inanother implementation, the protection film 123 may be a plurality oflayers each formed of one selected from the group of oxide, nitride, andan organic compound. The protection film 123 may include a groove 123 acorresponding to the second region 121 b.

FIG. 3 schematically illustrates a method of assembling thecrystallization substrate 110 and the reflection substrate 120, andscanning a laser beam onto an assembled structure.

The crystallization substrate 110 and the reflection substrate 120 maybe prepared and placed on one another as illustrated in FIG. 3. In thestructure in which the crystallization substrate 110 and the reflectionsubstrate 120 are placed on one another, the crystallization substrate110 and the reflection substrate 120 may be assembled such that theamorphous silicon layer 113 of the crystallization substrate 110 facesthe reflection panel 122 of the reflection substrate 120. Thus, theamorphous silicon layer 113 and the reflection panel 122 may be arrangedfacing each other with the protection film 123 interposed therebetween.

After the crystallization substrate 110 and the reflection substrate 120are placed on one another, a part of the amorphous silicon layer 113 maybe crystallized by scanning the laser beam thereto. In detail, after thecrystallization substrate 110 and the reflection substrate 120 areplaced on one another, the laser beam may be irradiated in a directionfrom the crystallization substrate 110 toward the reflection substrate120. The laser beam may be scanned perpendicularly to a surface of thereflection panel 122. The laser beam irradiated in a direction from thecrystallization substrate 110 toward the reflection substrate 120 passesthrough the crystallization substrate 110, but the laser beam isreflected in parts by the reflection substrate 120, as explained ingreater detail below.

For convenience of description, the laser beam is shown in FIG. 3 ashaving two aspects: first, laser beam A that penetrates a region thatdoes not have the reflection panel 122 therein; and, second, laser beamB that penetrates a region that has the reflection panel 122 therein. Ofthe laser beam irradiated in the direction from the crystallizationsubstrate 110 toward the reflection substrate 120, the laser beam B(proceeding toward the first region 121 a where the reflection panel 122is arranged) is reflected by the reflection panel 122. In contrast, thelaser beam A (proceeding toward the second region 121 b where thereflection panel 122 is not arranged) passes through the reflectionsubstrate 120.

A part of the laser beam B is absorbed by a first area 113 a of theamorphous silicon layer 113, which corresponds to the first region 121a. The other part of the laser beam B that passed through the first area113 a is then reflected by the reflection panel 122 and proceeds back tothe first area 113 a. Here, laser beam C denotes the laser beam that isreflected by the reflection panel 122 and proceeds back to the firstarea 113 a.

The first area 113 a of the amorphous silicon layer 113 may becrystallized by absorbing a part of the laser beam B proceeding from thecrystallization substrate 110 toward the reflection substrate 120 andthe other part of the laser beam B that is reflected by the reflectionpanel 122. In other words, the amorphous silicon layer 113 is notcrystallized with only the scanning of the laser beam A or B proceedingfrom the crystallization substrate 110 toward the reflection substrate120. Rather, the crystallization of the amorphous silicon layer 113 (toform a polycrystalline area) may be achieved by the scanning of thelaser beam B proceeding from the crystallization substrate 110 towardthe reflection substrate 120 and the laser beam C reflected by thereflection panel 122.

Further, the laser beam A corresponds to a second area 113 b of theamorphous silicon layer 113 (itself corresponding to the second region121 b of the second substrate 121 where no reflection panel exists).Here, only a part of the laser beam A is absorbed in the second area 113b (and no reflected laser beam exists), so that the second area 113 b ofthe amorphous silicon layer 113 is not crystallized.

The power of the laser beam (i.e., laser beams A, B) that is initiallyscanned may be adjusted such that the amorphous silicon layer 113 maynot be crystallized by the power of the initial transit of the laserbeam alone (i.e., by laser beam A or B), but may be crystallized by asum of the power of the laser beam (i.e., laser beam B in the reflectionregion) and the power of the laser beam C that is reflected.Accordingly, the crystallization of the amorphous silicon layer 113 maybe performed by the laser beam B proceeding toward the reflectionsubstrate 120 and the laser beam C that is reflected by the reflectionpanel 122. Thus, the amorphous silicon layer 113 may be selectively andeasily crystallized in correspondence with the pattern of the reflectionpanel 122. Also, various shapes of crystallizations of the amorphoussilicon layer 113 may be obtained according to the shape of the patternof the reflection panel 122.

Furthermore, according to the present embodiment, there is no need tocrystallize the entire surface of the amorphous silicon layer 113 andthen pattern a resultant crystallized silicon layer by aphotolithography method, as in a conventional technology. Thus, amanufacturing process may be simplified and manufacturing costs may bereduced.

In addition, according to the present embodiment, there is no need tocrystallize the amorphous silicon layer 113 directly by the initiallyscanned laser beam (i.e., laser beams A, B). Thus, the power of theinitially scanned laser beam (i.e., laser beams A, B) may be reduced sothat costs for scanning a laser beam may be reduced.

After a part of the amorphous silicon layer 113 is crystallized, thecrystallization substrate 110 and the reflection substrate 120 may bedisassembled.

FIGS. 4 and 5 illustrate cross-sectional views of stages in a method ofmanufacturing a thin-film transistor, according to a second exampleembodiment. FIG. 6 illustrates a cross-sectional view of an organiclight-emitting display device including a thin-film transistor,according to a third example embodiment.

Referring to FIG. 4, the crystallization substrate 110 is manufacturedby the above-described method of manufacturing a polycrystalline siliconlayer. The crystallization substrate 110 may include a crystallized areaof the amorphous silicon layer that was irradiated with a laser to formpolycrystalline silicon using the reflection panel 122, the reflectionpanel 122 having a pattern corresponding to areas where thin filmtransistors are to be formed. Here, the crystallized area is referred toas a polycrystalline silicon layer 213 a, and an uncrystallized area(i.e., an area with no corresponding reflection panel 122) is referredto as an amorphous silicon layer 213 b. Since the method ofmanufacturing the crystallization substrate 110 is described above,details thereof will not be repeated.

Referring to FIG. 5, a gate insulation film 222 may be formed to coverboth of the polycrystalline silicon layer 213 a and the amorphoussilicon layer 213 b. As the gate insulation film 222, an inorganicinsulation film, such as silicon oxide or silicon nitride, may be formedin, e.g., a single layer or a plurality of layers.

In the second example embodiment shown in FIG. 5, a gate electrode 223is formed on the gate insulation film 222 to correspond to a channelregion 114 a of the polycrystalline silicon layer 213 a. An interlayerinsulation film 224 is formed to cover the gate electrode 223.

The polycrystalline silicon layer 213 a is divided into the channelregion 114 a and source and drain regions 114 b and 114 c, which may beformed by doping the source and drain regions 114 b and 114 c withN-type or P-type impurities by using the gate electrode 223 as aself-aligning mask, after the gate electrode 223 is formed. In anotherimplementation, the channel region 114 a and source and drain regions114 b and 114 c may be formed by doping the channel region 114 a andsource and drain regions 114 b and 114 c with impurities after thepolycrystalline silicon layer 113 a is formed.

A source electrode 225 a and a drain electrode 225 b may be formed torespectively contact the source region 114 b and the drain region 114 cthrough respective contact holes.

Referring to FIG. 6, a planarization film 227 may be formed on theinterlayer insulation film 224 so as to cover the thin-film transistorTR. The planarization film 227 may be, e.g., an insulation film in asingle layer or a plurality of layers with a flat upper surface. Theplanarization film 227 may be formed of an inorganic material and/or anorganic material.

A via hole may be formed to expose the drain electrode 225 b of thethin-film transistor TR, the via hole penetrating the planarization film227. The thin-film transistor TR and a pixel electrode 310 formed in apredetermined pattern on the planarization film 227 may be electricallyconnected to each other through the via hole.

A pixel defining layer (PDL) 320 may be formed on the planarization film227, e.g., to cover the side portions of the pixel electrode 310. ThePDL 320 may define a pixel by covering the side portions of the pixelelectrode 310 with a predetermined thickness. Also, the PDL 320 mayincrease a distance between an end portion of the pixel electrode 310and an opposite electrode 340 (described below) so that generation ofarc at the end portion of the pixel electrode 310 may be prevented.

An organic film 330, including a light-emitting layer 331, and theopposite electrode 340 may be sequentially formed on the pixel electrode310. The organic film 330 may be, e.g., a low molecular weight or highmolecular weight organic film. When a low molecular weight organic filmis used, a hole injection layer (HIL), a hole transport layer (HTL), anemission layer (EML) 331, an electron transport layer (ETL), and anelectron injection layer (EIL) may be stacked in a single or combinedstructure. Suitable organic materials may include, e.g., copperphthalocyanine (CuPc), N,N′-Di(naphthalene-1-yl)-N,N′-diphenyl-benzidine(NPB), and tris-8-hydroxyquinoline aluminum (Alq₃).

When a high molecular weight organic film is used, only the HTL may beincluded in a direction along the pixel electrode 310 with respect tothe light-emitting layer 331. The HTL may be formed of, e.g.,poly-(2,4)-ethylene-dihydroxy thiophene (PEDOT) or polyaniline (PANI).The light-emitting layer may be independently formed for each red,green, and blue pixel, while the HIL, the HTL, the ETL, and the EIL maybe commonly applied for the red, green, and blue pixels, as commonlayers.

A sealing substrate 400 may be combined to the first substrate 111 by acombining member (not shown).

Above, an organic light-emitting display device is described as anexample display device having a thin-film transistor according to anembodiment. However, it will be appreciated that embodiments may beapplied to various display devices, including liquid crystal displaydevices, etc.

As described above, according to embodiments, an amorphous silicon layermay be selectively crystallized, i.e., crystallized only in the area(s)where crystallization is required. Further, embodiments may enable theuse of lower-power lasers while avoiding the need forpost-crystallization patterning.

Example embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation.Accordingly, it will be understood by those of skill in the art thatvarious changes in form and details may be made without departing fromthe spirit and scope of the present embodiment as set forth in thefollowing claims.

1. A method of manufacturing a polycrystalline silicon layer, the methodcomprising: providing a crystallization substrate, the crystallizationsubstrate having an amorphous silicon layer on a first substrate;providing a reflection substrate, the reflection substrate having afirst region with a reflection panel therein and a second region withoutthe reflection panel; disposing the crystallization substrate and thereflection substrate on one another; and selectively crystallizing theamorphous silicon layer by directing a laser beam onto thecrystallization substrate and the reflection substrate, and reflectingthe laser beam from the reflection panel.
 2. The method as claimed inclaim 1, wherein the crystallization substrate has a buffer layerbetween the first substrate and the amorphous silicon layer.
 3. Themethod as claimed in claim 2, wherein the first substrate includes atransparent material, the laser beam passing through the firstsubstrate.
 4. The method as claimed in claim 3, wherein the firstsubstrate is a glass substrate.
 5. The method as claimed in claim 1,wherein the reflection substrate includes: a second substrate, thereflection panel being a pattern on the second substrate; and aprotection film arranged on the second substrate to cover the reflectionpanel.
 6. The method as claimed in claim 5, wherein the second substrateincludes a transparent material, the laser beam passing through thetransparent material.
 7. The method as claimed in claim 6, wherein thesecond substrate is glass or quartz.
 8. The method as claimed in claim5, wherein the reflection panel includes a metal that is capable ofreflecting the laser beam, the laser beam being reflected from the metalto the crystallization substrate.
 9. The method as claimed in claim 8,wherein the metal has a reflectance of 50% or higher with respect to thelaser beam.
 10. The method as claimed in claim 5, wherein the protectionfilm includes an oxide, a nitride, or an organic matter, the laser beampassing through the protection film.
 11. The method as claimed in claim10, wherein: the protection film is a single layer formed of an oxide, anitride, or an organic material, or the protection film is a pluralityof layers, each layer being formed of an oxide, a nitride, or an organicmaterial.
 12. The method as claimed in claim 1, wherein, in thedisposing of the crystallization substrate and the reflection substrateon one another, the crystallization substrate and the reflectionsubstrate are brought into contact with each other so that the amorphoussilicon layer faces the reflection panel.
 13. The method as claimed inclaim 1, wherein selectively crystallizing the amorphous silicon layercomprises: directing the laser beam in a direction from thecrystallization substrate toward the reflection substrate; and forming apolycrystalline silicon layer by crystallizing a first area of theamorphous silicon layer corresponding to the first region of thereflection substrate as the laser beam directed toward the reflectionsubstrate is reflected by the reflection panel.
 14. The method asclaimed in claim 13, wherein the forming of the polycrystalline siliconlayer comprises: allowing the laser beam to pass through the first areaof the amorphous silicon layer; and crystallizing the first area of theamorphous silicon layer by using the reflection panel in the firstregion of the reflection substrate to reflect the laser beam passingthrough the first area of the amorphous silicon layer onto the firstarea of the amorphous silicon layer.
 15. The method as claimed in claim13, further comprising allowing the laser beam to pass through a secondarea of the crystallization substrate and the second region of thereflection substrate, wherein the second area of the amorphous siliconlayer is not crystallized and remains as the amorphous silicon layerafter the laser beam passes through the second area of the amorphoussilicon layer corresponding to the second region of the reflectionsubstrate.
 16. The method as claimed in claim 1, wherein the laser beamis scanned in a direction perpendicular to the reflection panel.
 17. Themethod as claimed in claim 1, further comprising disassembling thecrystallization substrate and the reflection substrate, afterselectively crystallizing the amorphous silicon layer.
 18. A method ofmanufacturing a transistor, the method comprising: providing acrystallization substrate, the crystallization substrate having anamorphous silicon layer on a first substrate; providing a reflectionsubstrate, the reflection substrate having a first region with areflection panel therein and a second region without the reflectionpanel; disposing the crystallization substrate and the reflectionsubstrate on one another; forming a polycrystalline silicon layer byselectively crystallizing the amorphous silicon layer by directing alaser beam onto the crystallization substrate and the reflectionsubstrate, and reflecting the laser beam from the reflection panel; andforming a channel region and source and drain regions in thepolycrystalline silicon layer.
 19. The method as claimed in claim 18,further comprising: disassembling the crystallization substrate and thereflection substrate, after selectively crystallizing the amorphoussilicon layer.
 20. The method as claimed in claim 18, furthercomprising: forming a gate insulation film on the crystallizationsubstrate to cover the polycrystalline silicon layer; forming a gateelectrode on the gate insulation film, the gate electrode correspondingto the channel region of the polycrystalline silicon layer; forming aninterlayer insulation film on the gate insulation film to cover the gateelectrode; and forming a source electrode and a drain electrode whichare disposed on the interlayer insulation film and electricallyconnected to the source region and the drain region of thepolycrystalline silicon layer, respectively.
 21. The method as claimedin claim 18, wherein forming the polycrystalline silicon layercomprises: directing the laser beam in a direction from thecrystallization substrate toward the reflection substrate; andcrystallizing a first area of the amorphous silicon layer correspondingto the first region of the reflection substrate as the laser beamdirected toward the reflection substrate is reflected by the reflectionpanel.
 22. The method as claimed in claim 21, further comprisingallowing the laser beam to pass through a second area of thecrystallization substrate and the second region of the reflectionsubstrate, wherein the second area of the amorphous silicon layer is notcrystallized and remains as the amorphous silicon layer after the laserbeam passes through the second area of the amorphous silicon layercorresponding to the second region of the reflection substrate.